1. Field
One embodiment of the present invention relates to an information processing apparatus having a real time clock which cannot easily be tampered, and a time information change method.
2. Description of the Related Art
Usually, time and date information of a personal computer is managed with a real time clock (RTC). Since the real time clock can easily be accessed by standard I/O of the computer, even a general user can easily change the time and date information. Therefore, when any countermeasure is not taken, the time and date information of the RTC is easily tampered. Therefore, use of the time and date information of the RTC for a security application involves risk.
In Jpn. Pat. Appln. KOKAI Publication No. 11-194851, a technology having two RTCs is disclosed for the purpose of improving the precision of time.
According to the above technology, in order to improve the precision of the RTC to be accessed by a CPU, another RTC having a high precision is prepared, and the time information of the RTC having the high precision is copied in the RTC. Therefore, the precision of the time information of the RTC can be kept, but any countermeasure against the tampering of the time information is not considered.